1. Field of the Invention
The present invention relates to an interpolation technology adapted to a picture motion, in particular to a deinterlacing apparatus which is capable of improving definition of a picture by performing edge direction detection and pixel interpolation.
2. Description of the Prior Art
In the conventional image processing method, a deinterlacing method is a method converting an interlaced scanning type image signal into a progressive scanning type image signal. It will now be described with reference to accompanying FIGS. 1 and 2Axcx9c2C.
FIG. 1 illustrates a picture in accordance with the general interlacing method.
As depicted in FIG. 1, in the interlaced scanning type image data, a picture of one frame is implemented with an odd field and an even field, namely, two fields.
However, according to a type of a display apparatus, a picture is implemented by processing the interlaced scanning type image signal as a progressive scanning type image signal used in a computer monitor etc. without processing it as the interlaced scanning type image signal.
Herein, in order to process the interlaced scanning type image signal on a display apparatus for processing the progressive scanning type image signal, an additional system for converting the interlaced scanning type image signal into the progressive scanning type image signal has to be installed inside of the display apparatus.
As depicted in FIGS. 2Axcx9c2C, a converting method for converting the interlaced scanning type image signal into the progressive scanning type image signal can be implemented many ways.
FIG. 2A illustrates a line repetition in accordance with the conventional technology.
As depicted in FIG. 2A, the line repetition implements one frame by repeating line information of the present field.
FIG. 2B illustrates an intra-field interpolation without motion-compensation in accordance with the conventional technology.
As depicted in FIG. 2B, the intra-field interpolation without motion-compensation implements one frame by inserting a former field line between the present field line.
FIG. 2C illustrates an intra-field interpolation in accordance with the conventional technology.
As depicted in FIG. 2C, the intra-field interpolation implements a new field by inserting xc2xd divided data of two lines into region between the two lines on one field.
The line repetition can be implemented as a simple hardware, however the image quality lowers after the interpolation using the line repetition method.
In addition, the intra-field interpolation without motion-compensation also can be implemented as a simple hardware, however a picture is deteriorated due to an error occurred in the interpolation of a motion picture.
And, the intra-field interpolation is better than the line repetition in the image quality and error occurrence aspect, however the picture is deteriorated when a still picture is interpolated.
In other words, as depicted in FIG. 2Axcx9c2C, the interpolation methods all have the image quality lowering problem after the interpolation.
Accordingly, a motion-compensation interpolation for interpolating the present picture by using field data of the former picture and field data of a picture to be implemented is suggested.
The motion-compensation interpolation divides a picture into a plurality of blocks and finds a motion vector about the each block by using timely consecutive field data on the basis of the present field data, and interpolates the present frame picture by referring the motion vector.
An image quality can be improved by the motion-compensation interpolation, however, it is implemented as a complicated hardware.
Accordingly, in order to solve the problem of the motion-compensation interpolation, a motion adaptive interpolation for interpolating a frame in accordance with a motion by assuming degree of the motion is suggested.
The motion adaptive interpolation can be implemented as a simple hardware on the comparison with the motion-compensation interpolation, and it can improve the image quality after the interpolation.
The motion adaptive interpolation comprises a Bernard method represented in the U.S. Pat. No. 5,027,201 and a Faroundja method represented in the U.S. Pat. No. 5,159,451 etc.
As described above, the conventional line repetition can be implemented as a simple hardware, however it lowers the image quality after the interpolation.
In addition, the conventional intra-field interpolation method can be implemented as a simple hardware also, however it has an error occurrence problem in the interpolation of the picture having motion or image quality lowering problem due to the deterioration.
In addition, the conventional intra-field interpolation is better than the line repetition in the image quality and error occurrence aspect, however the picture is deteriorated when a still picture is interpolated.
The conventional motion adaptive interpolation can be implemented as a simple hardware on the comparison with the motion-compensation interpolation, and it can improve the image quality after the interpolation. However, a stepped noise occurs due to a simple vertical interpolation in an edge having big motion.
In addition, the conventional motion adaptive interpolation uses a plurality of field memories and have a complicated processing process, accordingly manufacture cost of an implement circuit increases.
The object of the present invention is to provide a deinterlacing apparatus which is capable of improving definition of a picture by performing interpolation appropriately in accordance with a motion degree and an edge direction of a field to be interpolated.
The other object of the present invention is to provide a deinterlacing apparatus which is capable of detecting motion accurately by removing a high frequency noise element by performing low pass filtering after finding each BD (Bright Difference) by using an initially detected value when a BD (Brightness Difference) and a BPPD (Brightness Profile Pattern Difference) used for the motion detection are detected.
The another object of the present invention is to provide a deinterlacing apparatus which is capable of reducing manufacture cost of a circuit to be implemented by simplifying the circuit.
In order to achieve the above-described objects of the present invention, the deinerlacing apparatus in accordance with the present invention comprises a spatial interpolator for yielding intra-field interpolation pixel value with inputs of a pixel value of field data of a region to be presently interpolated and intra-field perimeter pixel value from the first field data, a temporal interpolator for yielding a field average value about a field picture to be interpolated by averaging a pixel value of the former field and a pixel value of the after field, a motion determining unit for yielding a motion degree value by yielding and comparing the BD and BPPD of the first field data, a motion expander for diffusing the motion degree yielded on the motion determining unit to the horizontal direction and vertical direction perimeter pixels hierarchically, a soft switch for mixing the interpolation pixel value yielded from the spatial interpolator in accordance with the motion degree value of the motion expander and the field average value yielded from the temporal interpolator, and a vertical line converter for converting the number of vertical lines of the present field data among the first field data so as to be appropriate to display by referring the interpolation line data on the soft switch.
In order to achieve the other object of the present invention, the BD/BPPD combiner of the present invention comprises a low pass filter for removing high frequency noise element by performing separately low-pass filtering of the BD (BDU) (BDC) (BDL), a first maximum value detector for detecting a first maximum value among the output signals of the low pass filter, a first mapper for mapping the first maximum value as a preset value when the first maximum value is more than a preset threshold, a second maximum detector for detecting a second maximum value among the BPPD (BPPDU) (BPPDC) (BPPDL), a second mapper for mapping the second maximum value as a preset value when the second maximum value is more than the preset threshold, and a third maximum value detector for determining the motion degree value by selecting a third maximum value among the output signals of the first and second mappers.